That's an excellent and very specific question! For a trash can that will live on a coastal boardwalk, battling constant salt air and moisture, the single most important factor is corrosion resistance. Based on that, here are the best material choices, ranked:
1. Marine-Grade Stainless Steel (The Top Tier Choice)
Look specifically for 304 or 316 stainless steel. Type 316, often called "marine-grade," contains molybdenum, giving it superior resistance to saltwater corrosion. It's the gold standard for marine environments. While it's a significant investment, it will last for decades with minimal maintenance—just occasional rinsing with fresh water. Avoid cheaper, non-marine grades as they can still pit and rust.
2. High-Density Polymer Plastics (The Practical Champion)
Heavy-duty plastics like linear polyethylene or polypropylene are fantastic options. Modern polymers are engineered to resist UV rays (so they won't become brittle and fade quickly) and are completely impervious to salt corrosion. They are lightweight, cost-effective, and often come in colors that blend with coastal scenery. Ensure it's a thick, robust construction to withstand wind and potential impacts.
Materials to Avoid:
* Regular Galvanized Steel: The zinc coating will eventually wear off, leading to rapid rust.
* Powder-Coated or Painted Metals: Salt air will find microscopic flaws in the coating, leading to bubbling and rust underneath.
* Low-Quality Plastic: Thin plastic will become brittle and crack from UV exposure.
Final Recommendation: For absolute, set-and-forget durability, choose marine-grade stainless steel. For the best balance of cost, performance, and longevity, a heavy-duty, UV-stabilized polymer trash can is your winning choice. Pair your selection with secure anchoring to handle coastal winds.